1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more specifically, to a method of forming a multi-layer wiring structure in the process for manufacturing a semiconductor device.
2. Description of Related Art
In one typical conventional method for manufacturing a semiconductor device having a multi-layer wiring structure, a first level level wiring conductor is formed on a silicon oxide film formed on a silicon substrate, and the first level wiring conductor is coated with an interlayer insulator film having a planarized upper surface. A contact hole is formed in the interlayer insulator film at a positioned of the first level wiring conductor.
Thereafter, a power supply layer for electroplating is formed to cover all exposed surfaces. Then, a photoresist layer is deposited on the power supply layer, and then, patterned so as to form grooves for formation of a second level wiring conductor. Some of the grooves is composed to include the contact hole. Then, a second level metal layer is deposited on the power supply layer by an electroplating process using the patterned photoresist layer as a mask.
Thereafter, the photoresist layer is removed so as to form second level wiring conductors, and then, the power supply layer is removed by a sputter etching using the second level wiring conductors as a mask.
In the above mentioned conventional method for manufacturing a semiconductor device, after the second level wiring conductor layer is formed by the electroplating, the sputter etching is performed in order to remove an unnecessary portion of the power supply layer for electroplating. In this process, a portion of a removed metal of the power supply layer is deposited on side surfaces of the second level wiring conductors. A portion of the removed metal deposit adhered to the side surfaces of the second level wiring conductors peels off from the side surfaces of the second level wiring conductors in succeeding processes. As a result, adjacent second level wiring conductors are often short-circuited, with the result that the fabrication yield and the reliability of the products falls down.